Not sure what you mean. In it, the white bishop would be on b5, then black plays a6, moving the bishop to a4. Do you mean Bb5? It's to attack the defender of black's e5 pawn.
What's the idea of Nb5 in Ruy Lopez?
Bb5 attacks the d4 and e5-squares by pressuring the c6-knight. Yes, Black can push away the bishop with ...a6 and ...b5, but that creates weaknesses on the queenside to be exploited later. That's why the Ruy Lopez is superior to the Giuoco Pianissimo (1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.d3 Nf6 5.c3, etc.).
Bb5 attacks the d4 and e5-squares by pressuring the c6-knight. Yes, Black can push away the bishop with ...a6 and ...b5, but that creates weaknesses on the queenside to be exploited later.
Probably even more important is the fact that the bishop is safer in b3 than c4. Just look at continuation 3. Bc4 Nf6 4. d4 exd4 5. e5 d5! which clearly wouldn't be possible with the bishop in b3. There are many positions in Italian where d5 attacking Bc4 is an important resource for black.
The position after 4... b5 5. Bb3 is almost certainly better for white than the one after 3. Bc4 and for this reason black usually isn't in such a hurry to drive the bishop to b3 in Ruy Lopez.
Also, even though white moves the bishop second time with Ba4, black doesn't really win a tempo as a6 isn't a developping move!
If Bb5 wastes a tempo, so does a6 :p
It's developing with a threat, and white can castle very early. It happens to lead to rich and complicated games, so the opening in general is still very well known.
For example black gets lots of queenside space, but he's not developed yet. If white hits in the center and or queenside with a pawn break will this be a liability for black? Or can black use the space to his advantage? This and other ideas are in balance, so it's fun to play and see who can make their position work best for them.
Bb5 is the best way to get the bishop to c2, without risking the central sack Nxe4 after something like Bc4.
What do you think of these 2 games? Is white really so bad? I think it's the main reason to play Ruy. My game and Kasparov's one.
Bb5 is the best way to get the bishop to c2, without risking the central sack Nxe4 after something like Bc4.
Notice Nxe4 is illegal
Bb5 is the best way to get the bishop to c2, without risking the central sack Nxe4 after something like Bc4.
Notice Nxe4 is illegal
In an alternate universe, black never plays Nf6, and also people who have played for decades sometimes think knights move diagonally.
What's the idea of Nb5 in Ruy Lopez? Since after that Black moves a6 and white Bishop ends in a4.
Isn't white wasting a tempo?